It’s tough to secure a round metal fixture with a flat jaw plier.
You may end up grabbing it so tightly that you crush the wire. This plier’s non-marring jaws are grooved for a tight grip while bracing and adjusting round wire frame components including round metal temples. Great for bracing rimless while making adjustments and tweaking some pad arm styles. The Guild style features 1mm and 2mm groove diameters. Premium has a single 2mm groove.